There's a long running debate among archaeologists about who the first humans to arrive in the Americas really were. There are two distinct sets of ancient tools that we find in North America, called the Western Stemmed and Clovis traditions. The question is, did the cultures that made Western Stemmed tools come to the Americas at the same time as the Clovis toolmakers? Or did one evolve into the other? Both were active at around the same time period, around 11,000 years ago, but the majority of evidence has pointed towards Western Stemmed tools arising after Clovis. A set of new radiocarbon dates, however, has pushed those dates around, and revealed two contemporary cultures rather than one changing into another.

Research newly published in Science dates human occupation of a Western Stemmed site at Paisley Caves in Oregon back to 12,450 radiocarbon years ago, with the points themselves dated back to 11,340 radiocarbon years ago. The older dates are associated with human coprolites (fossilized poop, in case you didn't know), which were similar to the ones found at the same period as the stone tools.

This pushes back the earliest dates of this culture some 14,000 years, to the point where it was concurrent with Clovis, or possibly even preceded it — which has some major implications for the culture of the early Americas. Study co-author Loren Davis said in a release:

"These two approaches to making projectile points were really quite different, and the fact that Western Stemmed point-makers fully overlap, or even pre-date Clovis point makers likely means that Clovis peoples were not the sole founding population of the Americas."

This means quite a lot for our understanding of how humans first arrived on this continent, as there were two different cultures coexisting on the continent from an incredibly early time.